Potassium Disorders

Question 1

Normal serum K level

Answer 1

3.4-5.0 mEq/L

Question 2

Aldosterone

Answer 2

Increases Na reabsorption and K secretion

Question 3

K secretion is dependent on what 4 things

Answer 3

Aldosterone
Tubular flow rate
Luminal delivery of Na
Acid base status

Question 4

Aldosterone paradox

Answer 4

Na and K are controlled separately by the same hormone
Suppressed PT reabsorption of Na when ECV is full increases the flow rate past principal cells and increases distal Na delivery - increases K excretion

Question 5

Clinical manifestations of hyperkalemia

Answer 5

Weakness
Nausea
Paesthesias
Palpitations
Arrhythmias

Question 6

4 steps in treating hyperkalemia

Answer 6

Stabilize cellular membrane (calcium gluconate)
Shift K into cells (insulin and glucose IV)
Promote K excretion (IVF, promote GI excretion, hemodialysis)
Treat underlying condition and stop offending agents

Question 7

Symptoms of hypokalemia

Answer 7

Muscle weaknes
Cramping
Ileus
Cardiac arrhythmias

Question 8

Hypomagnesium effect on K

Answer 8

HypoMg releases baseline inhibition of Mg on ROMK channel, causing increased K secretion and low K
Also many causes of hypoK also cause hypoMg